The present invention relates to a fixing apparatus for use with an electrophotographic copying machine or the like.
In one of prior art fixing apparatuses for copiers or the like, a fixing roller has a rubber layer thereon and a heater thereinside and is engaged by a pressure roller. These rollers are rotated to process a sheet fed thereto so that a toner or like material carried on the sheet is fixed permanently thereon. In this type of fixing apparatus, the toner, therefore the sheet, is apt to stick to the periphery of the fixing roller. It has been customary to employ sheet separator pawls which are resiliently engaged with the periphery of the fixing roller at their free ends, thereby forcibly peeling a leading end portion of a sheet from the fixing roller.
A problem has existed in such a type of fixing apparatus in that the sheet separator pawls, which are fixed in place, constitute an obstruction to the access when a sheet jammed between the fixing and pressure rollers has to be removed. Efforts heretofore made to solve this problem may be typified by designing a fixing apparatus so that the sheet separator pawls may be movable toward and away from the fixing roller. In this apparatus, upon sheet jam, the sheet separator pawls are moved clear of the fixing roller so that the sheet may be readily accessible through the open space around the fixing roller.
The sheet separator pawls so movable relative to the fixing roller are provided with a tendency that their free ends move toward the fixing roller at all the time. When the pawls are once spaced from the fixing roller for settling a sheet jam or for cleaning purpose and then moved back into contact with the fixing roller, their free or separating ends are apt to stick in the periphery (rubber layer) of the fixing roller due to the inherent tendency. This may disenable the pawls to restore the original position or damage the roller surface. Should the pawls be forcibly pulled out from the fixing roller, the free ends of the pawls and/or the periphery of the fixing roller would be damaged. Any damage to the roller surface will destruct an anti-offset layer on the roller to further enhance sticking of the sheet to the roller while allowing even the flaws to be transferred onto the surface of the sheet to be fixed.